/// <summary> Picks randomly an item from the collection. </summary>
/// <typeparam name="T"> The type of items in the collection. </typeparam>
/// <param name="items"> The collection of items to pick from. </param>
/// <param name="randomisationStep"> The current randomisation step. </param>
/// <returns></returns>
public T GetRandom <T>(IEnumerable <T> items, ERandomisationStep randomisationStep = ERandomisationStep.NotRelevant)
{
var itemType = typeof(T);
if (items.IsEmpty())
{
if (itemType.IsEnum)
{
var defaultEnumerationItem = itemType.GetEnumerationItems <T>().FirstOrDefault(item => item.ToString() == EWord.None);
if (defaultEnumerationItem is null)
{
throw new Exception(ECoreLogMessage.EnumerationHasNoDefaultItem.Format(itemType.ToStringLikeCode()));
}
return(defaultEnumerationItem);
}
if (itemType.IsValueType)
{
throw new Exception(ECoreLogMessage.NothingToSelectFrom);
}
if (itemType.IsClass)
{
return(default);
protected override T GetRandomCore <T>(IEnumerable <T> items, ERandomisationStep randomisationStep)
{
if (typeof(T) == typeof(EBranch) && randomisationStep == ERandomisationStep.MainBranchWhenSelectingByCategories)
{
var branches = items.OfType <EBranch>();
var branchSet = new BranchSet(branches);
AddIfMissing(branchSet, branches);
var mainBranchOccurrences = _mainBranchOccurrences[branchSet];
var selectedBranch = EBranch.None;
if (mainBranchOccurrences.Values.AllEqual())
{
selectedBranch = base.GetRandomCore(items, randomisationStep).CastTo <EBranch>();
}
else
{
var mostOccurences = mainBranchOccurrences.Max(keyValuePair => keyValuePair.Value);
var leastOccurrences = mainBranchOccurrences.Min(keyValuePair => keyValuePair.Value);
var leastOccurredMainBranches = mainBranchOccurrences.GetKeyWhereValue(occurrenceCount => occurrenceCount == leastOccurrences);
IncreaseMainBranchWeights(branchSet, leastOccurredMainBranches, mostOccurences - leastOccurrences);
selectedBranch = GetRandomMainBranch(branchSet, branches);
ResetMainBranchWeights(branchSet, branches);
}
mainBranchOccurrences[selectedBranch] += EInteger.Number.One;
return(selectedBranch.CastTo <T>());
}
else
{
return(base.GetRandomCore(items, randomisationStep));
}
}
protected virtual T GetRandomCore <T>(IEnumerable <T> items, ERandomisationStep randomisationStep)
{
return(items.ToList()[_generator.Next(items.Count())]);
}